The present invention relates to a drive bogie for a rail vehicle and to a rail vehicle equipped with at least one such bogie.
Customarily, a drive bogie comprises axles resting on the rails of the track and supporting a chassis, with the interposition of a suspension known as the primary suspension. The body of the railway vehicle rests on the chassis of this bogie, with the interposition of a suspension known as the secondary suspension.
Each drive bogie is fitted with means for driving each axle, which means comprise at least one motor and at least one reduction gearbox equipped with a wheel for driving the corresponding axle. There are also means allowing the railway vehicle to support the motors and the reduction gearboxes.
It is advantageous to have the mass of the drive means supported by a mechanical part of the vehicle which is as suspended as possible. This plays a part in reducing the loadings exerted on the rails by the drive bogie and makes it possible to increase the speed of the railway vehicle. From this standpoint it is preferable to have the masses of the motors and of the reduction gearboxes supported by the body of the vehicle and, failing that, by the chassis of the bogie, the solution of having the axles support these masses being the most unfavorable solution.
Incidentally, the body of the vehicle, the chassis of the bogie and the axles are free to move with respect to one another. Now, as the drive wheel of the reduction gearbox has to be secured to the axle, the higher up the members from which the motor and the reduction gearbox are suspended, the more complex will be the transmission between the suspended motor and this drive wheel fixed to the axle.
A compromise has therefore to be found between suspending these masses solely from the axle, which is simple to implement but which allows only low speeds, and suspending the masses from the body, which allows high speeds but which is complex in technical terms.
A first solution consists in suspending a geared motor unit from the body of the vehicle and in installing an additional reduction gearbox on the axle, these two reduction gearboxes being connected by a constant-velocity joint. This solution does, however, have drawbacks in that it is necessary to use two separate reduction gearboxes. What is more, the use of a constant-velocity joint, which is particularly expensive, leads to high costs.
An alternative solution has been proposed. It consists in suspending the reduction gearbox from the chassis of the bogie, at the opposite end to the axle. Incidentally, the motor is fixed permanently to the chassis, the reduction gearbox and the motor usually interacting via a curved-tooth coupling.
This arrangement, although relatively advantageous in terms of cost, does have other drawbacks. Specifically, the masses of the motor and of the reduction gearbox are supported not by the body of the vehicle but by the chassis of the bogie, which means that the axles exert relatively high loads on the rails. What is more, mounting the motor permanently on the chassis leads to the emergence of high mechanical loadings exerted on this chassis.
In order to alleviate the various drawbacks of the prior art as mentioned hereinabove, the invention proposes to produce a railway vehicle drive bogie in which the masses of the motors and of the reduction gearboxes are supported, to a large extent, by the body of the vehicle, via a low number of mechanical parts which have a simple structure and are inexpensive.
To this end, the subject of the this invention is a drive bogie for a rail vehicle, intended to support a body of the said vehicle, the said drive bogie comprising axles resting on rails, a chassis resting on the said axles and means for driving each axle, including a motor, a reduction gearbox and means of transmission between the motor and the reduction gearbox, means being provided to allow the vehicle to support the drive means, characterized in that the said means for supporting drive means comprise means for suspending the reduction gearbox or the motor from the body of the vehicle, these means being articulated to the reduction gearbox or to the motor, and to the body, means for articulating the motor to the chassis of the bogie about a roughly horizontal axis, and means for connecting the motor to the reduction gearbox, these means being articulated both to the motor and to the reduction gearbox.
According to other features of the invention:
when viewed from the side, the point of articulation of the reduction gearbox or of the motor to the suspension means lies between the center of gravity of the reduction gearbox and the center of gravity of the motor;
the moment exerted by the reduction gearbox on the said articulation point is approximately equal to the moment exerted by the motor on this articulation point;
when viewed from above, the reduction gearbox and the motor are transversely offset with respect to each other, the point of articulation of the suspension means to the reduction gearbox or to the motor being located between the center of gravity of the reduction gearbox and the center of gravity of the motor;
the means for suspending the reduction gearbox or the motor from the body of the vehicle are articulated to the reduction gearbox or to the motor, and to the body, at least about a horizontal axis;
the suspension means comprise an approximately straight connection rod stretching roughly vertically between the reduction gearbox and the body of the vehicle;
the means of articulation of the motor to the chassis comprise two arms secured to the housing of the motor, these arms being articulated to the chassis about the said horizontal axis;
the means for connecting the motor to the reduction gearbox are articulated to the motor and to the reduction gearbox at least about a horizontal axis;
the means for connecting the motor to the reduction gearbox comprise a link rod which, when viewed from the side, is in the shape of a C, the two ends of this link rod, one of them articulated to the motor and the other to the reduction gearbox, being located roughly one below the other;
the means of transmission between the motor and the reduction gearbox comprise a curved-tooth coupling;
the reduction gearbox comprises a driven wheel driven by the motor, a drive wheel secured to the axle and an intermediate wheel.
Another subject of the invention is a railway vehicle comprising at least one drive bogie and a body resting on the or each drive bogie, characterized in that the or each drive bogie is as defined hereinabove.